Proceedings: 8th Tall Timbers Fire Ecology Conference 1968 Fire Ecology of the Valdivian Rain Forest* E. J. WILHELM, JR. University of Virginia ALTHOUGH less widespread than formerly, there exists perhaps nowhere in Latin America a better example of a tem­ perate-marine forest than in the Lake District of southern Chile and Argentina. This forest reaches its optimum growth on the slopes of the Chilean watershed between 39° and 42° S (Fig. 1). Here thrives the exuberant plant community known as the Valdivian rain forest. The extraordinary growth of trees and shrubs, the thick stands of bamboo, the imposing lianas artistically twisting round the trunks of the massive beeches, and the luxuriant upholstering of epiphytes recall impressions of the tropical rain forest (Fig. 2). The sole purpose .in presenting this paper is to emphasize how man, through the agency of fire, has drastically altered the Valdivian rain forest ecosystem, and to conclusively show that most ruthless forest destruction has occurred in the past 75 years. BRIEF DESCRIPTION OF THE RAIN FOREST With just reason, the rain forest has been designated by Dimitri • Data for this paper were collected during a 1961-62 field investigation to Patagonia, Argentina-Chile. The research project was sponsored by the National Academy of Sciences-National Research Council, Foreign Field Research Program, and financed by the Geography Branch, Office of Naval Research under contract number Nonr-2300 (09). 55 E. J. WILHELM, JR. VALDIVIAN RAIN FOREST o Former Distribution 1 ~ Present (1961) 36° Distribution ( ~ Data Taken "From Lerman ..:i ;IICI 1962 n Q 20 40 J: \ KM. m ." r- Z ~ m \ .... 38° o n r' Z ." ). » n 0 40° n m ~ Z 42° FIG. 1. Past and present (1961) distributions of the Valdivian rain forest. (1962: 29) and others as the Valdivian selva, in which numerous lianas, epiphytes, mosses, lichens, and other plants morphologically resemble a tropical rain forest. A special feature of the Valdivian rain forest is the leathery leaves, a characteristic resembling the physiognomy of dry region plants. In this manner the trees probably protect themselves from an excess of rain as well as short periods of aridity. Although dominated by the southern beeches, like the coihue (Nothofagus dombeyi), a great variety of woody plants exists in the rain forest. Most are broad-leaved evergreen trees which resemble 56 FIRE ECOLOGY OF VALDIVIAN RAIN FOREST FIG. 2. The Valdivian rain forest. magnolias and laurels found in the United States. In the better drained spots throughout the forest the highest tier is made up of coihue (Fig. 3), generally 40-45 meters high. Beneath these stately trees at 25-30 meters lies the understory of maniu bemhra (Saxego­ thea conspicua) and hua-huan (Laurelia philippiana). Poorly drained or swampy habitats permit the alerce (Fitzroya cupressoides) to grow in dense unmixed stands. In drier soil this giant sequoia-like conifer mixes with beeches like the coihue, and with the conifers maniu hemhra and cipres de las Guaytecas (Pilgerodedron uviferum). The association of coniferous with broad-leaved evergreen species is another characteristic feature of the ecosystem. The alerce perhaps best represents a tree species of the Valdivian rain forest more than any other type (Fig. 4). Its northern limit originally included the coastal mountains of Valdivia Province, Chile, at elevations above 300 meters. It then extended south to 57 E. J. WILHELM, JR. FIG. 3.. The coihue (N othofag'/,ls dombeyi) dominates the Valdivian rain forest. Ii: oftenattairis a diameter of 3-4 meters at breast height. Chiloe Province, Chile, and adjacent Chubut Province, Argentina. It. was also found on moist sites in the central valley between Lake Llanquihue and Puerto Montt. Presently, however, alerce stands are restricted to a few inaccessible localities. The largest and best preserved tract in Chile occurs in a 50-kilometer-long area southeast of Puerto Montt on the Hornopiren Peninsula (Fig. 1). In a general way the appearance of the alerce resembles that of the coastal redwood (Sequoia sempervirens) of California. Like the redwood, the sapwood is yellow and the heartwood is light red to cinnamon. The alerce prefers low, marshy, peat-like soils, but in some areas of Argentina and Chile it reaches an altitude of 900 meters above sea level. An evergreen which craves humid conditions, it has an unquenchable thirst for water. Some specimens thrive under 58 FIRE ECOLOGY OF VALDIVIAN RAIN FOREST conditions of more than 5,000 millimeters of annual precipitation. The tree reaches diameters of 3 to 4 meters and heights in excess of 50 meters under the favorable criteria of damp, peaty soil and humid atmosphere. THE HUMAN ELEMENT Aboriginal man, prior to the corning of the European, apparently was not an integral part of the Valdivian rain forest ecosystem. Although archeological excavations are lacking for the rain forest zone, historical evidence at least points to the conclusion that Arau­ canian Indians lived generally outside of the primeval forest and utilized it only when absolutely necessary. Most of the southern Araucanians dwelled along the Pacific coast, adjacent bays, and the shores of nearby inland freshwater lakes where the primal needs of FIG. 4. The alerce (Fitzroy a cupressoides) grows in poorly drained habitats in the Valdivian rain forest. In general appearance it resembles the coastal redwood (Sequoia sempervirens) of California. 59 E. J. WILHELM, JR. life were satisfied. The adjoining rain forest harbored a ready source of building materials, fuel, and some wild game and plant­ life. Thus it was advantageous for most Indians to build their settle­ ments beside the water-bodies as close to the rain forest as possible. The coastal southern Araucanians, however, were not typical slash­ and-burn agriculturalists like their northern inland Indian neighbors. Faron (1961: 18) believes that it is even misleading to think of the northern Araucanians, prior to 1600, as field farmers, since equipment for field cultivation did not appear until the colonial period. The coastal southern Araucanians remained small-scale garden cultivators at best during the pre-colonial period, and depended almost entirely upon the sea for their livelihood. It is quite apparent that the southern Araucanians knew fire long before Spanish contact. Fire was used for cooking, heating, burning out dugout canoes, and to a lesser degree, for clearing portions of the rain forest. Bullock (1911: 31) states that cultivation of pota­ toes occurred in open glades in the rain forest. These small openings were certainly formed by burning the rain forest and were located in close proximity to Indian settlements. Nevertheless, aboriginal burning was definitely restricted to a narrow segment of the Val­ divian rain forest and thus had a minor influence on the ecology of the ecosystem. Spanish immigrants occasionally penetrated the southern forests between the 17th and 19th centuries, only to be met by hostile native resistance. It was apparent from the beginning of Spanish colonization that the central region of Chile was more conducive to settlement, thus the southern forested region was bypassed. Chilean independence from Spain in 1818 awakened national interest in south Chile. The land tenure policy, introduced by the Spanish and largely retained after Chile's independence, combined with giving private initiatve a free hand in clearing forest lands. This plan had the result that much rain forest of south Chile came to be considered private property. Further, by clearing the rain forest with fire the settlers were destroying suitable habitat for offensive Indians. This was the beginning of the extensive forest burning in south Chile, although still somewhat restricted as to area. The southlands were opened fully to Europeans, and in the 1850's 60 FIRE ECOLOGY OF VALDIVIAN RAIN FOREST German immigrants began to buy and clear land between Valdivia and Puerto Montt. The German immigrant of the late 19th and early 20th centuries was the epitome of ruthless land clearing. According to Fergusson (1943: 50), earliest efforts were almost entirely devoted to clearing the extensive forests for agricultural crops and grazing. From the beginning the forest was regarded as an impediment to be cleared away as rapidly as humanly possible. After making a clearing in the forest, the German settler constructed a temporary log house and prepared a field to plant his crops. Stumps, charred trunks, and surface roots prevented the Germans from using a plow, so they used a hoe or a dibble. Fire was quickly and easily employed in the warmer months when least precipitation fell. The usual method of firing the land centered on selecting dead but standing trees. Branches, twigs, and other organic debris were piled up around the base of the tree, then set afire. By firing several "match" trees in any given stand, the fire quickly spread to adjoining live trees. Only a very few highly selective trees were cut beforehand and utilized for domestic pur­ poses. These fires were very destructive, not only killing and injuring the trees left in the stand (often up to 80% of the original volume), but also spreading far outside the original stand to adjacent un­ burned and uncut areas. ECOLOGICAL CHANGES TO THE ECOSYSTEM In spite of controversies as to its true impact, fire has greatly modified the composition of vegetation in the rain forest. This was vividly displayed in an area between Lakes Llanquihue and T odos los Santos (Fig. 5). Prior to 1900, part of this area (15 kms. long by 5 kms. wide) was covered by an alerce forest. Tree specimens reached, according to nearby inhabitants, heights of 40 meters and diameters at breast height of 3 meters (Fig. 6). The land was ac­ quired by several German families around 1900, and they im­ mediately began firing the land in order to create agricultural fields.